1. Field of the Invention
This invention relates to apparatuses and methods for mixing gases. The apparatuses and methods can be used for mixing, for example, hydrogen and nitrogen gases. The invention has particular applicability to the manufacture of an electronic device.
2. Description of the Related Art
Mixtures of gases are used in a wide range of industries for various purposes. For example, mixtures of high-purity gases are typically used in the semiconductor manufacturing industry for processing semiconductor substrates. High-purity gases include, for example, in a nitrogen and hydrogen gas mixture, less than about 100 ppb of water and less than about 100 ppb of oxygen impurities.
Gas mixtures are commonly provided by automatic gas panel systems. Typical gas panel systems receive a gas mixture from high-pressure gas cylinders. Although automatic gas panel systems that utilize such gas cylinders have been subject to improvements, use thereof typically presents several disadvantages. For example, the purity levels of the gas mixtures provided therefrom can be inconsistent. In addition, monitoring and maintenance of the gas panel systems that utilize gas cylinders can be time consuming and costly. For example, maintenance of gas panel systems that utilize gas cylinders typically requires replacing used gas cylinders on a frequent basis, cycle purging cylinder connections to reduce or prevent atmospheric contamination, manually setting the gas cylinders in an on-line apparatus, and monitoring gas cylinder and delivery pressures.
In addition, the use of gas panel systems that utilize gas cylinders can be susceptible to human error. For example, replacing empty gas cylinders is typically a repetitious procedure. Problems can arise with incorrectly adjusted cylinder valves, process delivery valves and/or regulators. Further, the cost of operating automatic gas panel systems that utilize gas cylinders can be significant. The various potential problems with using gas panel systems can cause process interruptions which can be extremely costly, especially in the semiconductor manufacturing industry.
In addition to automatic gas panel systems, manual mixers can be used to provide gas mixtures. Manual mixers for producing oxygen and helium mixtures and nitrogen and hydrogen mixtures have been designed and operated by Air Liquide Corporation located in Dallas, Tex. Such manual mixers typically require close monitoring during the operation and maintenance thereof.
Low-purity gas mixers are also used to provide gas mixtures in applications which do not require a high-purity level, for example, welding applications. Low-purity gas mixers are available, for example, from Thermco Instrument Company located in Laporte, Ind. Low-purity gas mixers typically employ gas analyzers to monitor the blend ratio of the gases in the mixer. However, these gas mixers are unable to provide gas mixtures of high-purity such as the gas mixtures as required in the semiconductor manufacturing industry.
In view of the foregoing, there is a need in the art for gas mixing apparatuses and methods that overcome the disadvantages of current gas mixing devices discussed above, and especially for provision of high-purity and/or ultra-high-purity gas mixtures.
Accordingly, it is an object of the present invention to provide apparatuses and methods for mixing gases that reduce or eliminate the use of gas cylinders.
The apparatuses and methods for mixing gases in accordance with the invention can reduce the amount of monitoring and operator input during use thereof, and can provide a gas mixture having an increased consistency in mixture concentration. Furthermore, the apparatuses and methods for mixing gases in accordance with the invention can reduce or eliminate the occurrence of back diffusion of gases.
Other objects and aspects of the present invention will become apparent to one of ordinary skill in the art upon review of the specification, drawings and claims appended hereto.
The foregoing objects are met by the apparatuses and methods of the present invention. According to a first aspect of the present invention, an apparatus for mixing gases is provided, suitable for use in the manufacture of an electronic device. The apparatus comprises:
(a) a gas mixing manifold;
(b) a first, bulk gas source connected to introduce a flow of a first gas to the manifold;
(c) a second gas source connected to introduce a flow of a second gas to the manifold, wherein the first and second gases are mixed in the manifold, thereby forming a gas mixture; and
(d) a conduit connected to one or more point of use for introducing a flow of the gas mixture thereto.
According to a further aspect of the present invention, a method for mixing gases is provided, suitable for use in the manufacture of an electronic device. The method comprises the steps of:
(a) providing a gas mixing manifold;
(b) introducing a flow of a first gas to the manifold from a first, bulk gas source;
(c) introducing a flow of a second gas to the manifold from a second gas source, wherein the first and second gases are mixed in the manifold, thereby forming a gas mixture; and
(d) introducing a flow of the gas mixture to one or more point of use.